This invention concerns a needle assembly, particularly but not exclusively a needle assembly for use with syringes, drips, vacutainers or other instruments which include a needle for administering a substance to a body or taking a sample therefrom; and also instruments including such an assembly.
Needles are used extensively in medicine, veterinary science and elsewhere for providing injections, drips and the like. Needles can be used when taking samples and also administering substances by injection or a drip. Medical staff and others can often injure themselves on needles. When dealing with infected persons or animals this can produce a considerable risk of infection to the user. Accidents can also occur where discarded needles are found, and particularly by children. When such needles have been used by persons administering illegal drugs the risk of a serious infection is increased.
The term xe2x80x9cneedle instrumentxe2x80x9d as hereinafter used in this specification is to be understood as covering any instrument which requires a needle or other elongate projection for inserting into a body, which may be usable for instance for administering a substance to a body or taking a sample therefrom, or puncturing the skin. The needle/projection may be hollow or solid. Examples of such instruments are indicated above.
According to the present invention there is provided a needle assembly, the assembly comprising a needle and a housing in which the needle is located and from which the needle can selectively extend, the assembly being arranged such that the needle can only extend from the housing when in a particular alignment relative to the housing.
The needle may have a non-circular cross-section for at least part of its length, and the housing may have a restrictive part with a non-circular cross-section through which the needle can only extend when in a particular alignment relative thereto.
The housing preferably comprises a first part rigidly fixed relative to the needle and a second part movable relative to the needle, the second part being movable when the needle is in the particular alignment to a use position wherein the needle extends from the housing. The second part preferably includes the restrictive part.
The first part is preferably in the form of a receptacle which movably locates a portion of the second part and from which a further portion of the second part extends, with a greater portion of the second part being located in the first part when in the use position.
A component of the second part is preferably slidably movable within the first part. The needle preferably extends through the first part. A free end of the second part may have a roughened surface to be non-rotatably engageable in use against a person""s skin.
The second part is preferably spring urged away from the use position and/or the particular relative alignment with the needle. The second part is desirably spring urged away from the use position and the particular relative alignment, and desirably by a single spring, which spring may comprise a helical spring which may extend around the needle, and is desirably substantially co-axial therewith.
First means are preferably provided for selectively retaining the needle and second part in said particular alignment when the needle is located wholly within the housing.
Second means are preferably provided for selectively retaining the needle and second part in said particular alignment when the needle extends from the housing.
The first retaining means may comprise one or more projections on a one of the first or second parts which is selectively locatable in a corresponding recess or recesses in the other of the first or second parts.
Alternatively, the first retaining means may comprise a projection on the second part which is engageable against an abutment on the first part when in the particular alignment, and the projection and abutment desirably have sufficient depth for engagement to continue as the needle is moved to extend from the housing, and desirably until the second retaining means becomes operative.
The second retaining means may comprise an elongate projection on a one of the first or second parts which is selectively slidably locatable in a corresponding recess in the other of the first or second parts. Alternatively the second retaining means may comprise an elongate recess on a one of the first or second parts which selectively slidably locates a corresponding projection on the other of the first or second parts. The elongate projection or recess is preferably provided on the first part.
In alternative embodiments guide means may be provided which only permit the second part to move into the first part when in said particular alignment. Said guide means may comprise an elongate projection on the first part which only permits movement when engaging in a recess in the second part. The recess preferably extends for the whole length of the second part.
A plurality of recesses are preferably provided, with some of the recesses being blind by only extending for a part of the length of the second part. The blind recesses are preferably of a length such that when the elongate projection reaches the closed end thereof, the needle has not yet started to extend from the housing.
As an alternative to an elongate projection, a slidable projection may be provided.
Means may be included to provide a visual indication when the needle is in the particular relative alignment, and said means may comprise alignable markings on the first and second parts.
The first part may comprise a cylinder and said component of the second part preferably comprises a member which slidingly fits in the cylinder.
The restrictive part of the housing may be provided substantially at the end of the second part of the housing furthest from the first part thereof.
The restrictive part and/or the needle may have a substantially oval or elliptical cross-section, and desirably both are substantially oval or elliptical with the needle only slidingly fitting through the restrictive part when in a substantially parallel alignment thereto.
Alternatively the restrictive part and/or the needle may have a polygonal cross-section. Desirably the restrictive part and/or needle are of a triangular cross-section, and desirably both have a triangular cross-section with the needle only slidingly fitting through the restrictive part when in a substantially parallel alignment thereto.
The second part between said component and the restrictive part may comprise a tube through which the needle is movable, and the tube preferably has a circular cross-section.
The first part preferably rigidly mounts the proximal end of the needle.
In an alternative embodiment the housing between the first and second parts comprises a variable length portion such that the housing can reduce in length to permit the needle to extend therefrom.
The housing may comprise a third part located between the first and second parts, and a variable length portion is desirably provided between the first and third parts. A variable length portion may also be provided between the second and third parts.
Third means are preferably provided for selectively retaining the needle and the second part in said particular alignment.
The third retaining means may comprise one or more projections engageable in a corresponding recess or recesses, which recess or recesses are non-rotatably arranged relative to the needle. Alternatively, the third retaining means may comprise one or more recesses in which a corresponding projection or projections are engageable, which projection or projections are non-rotatably arranged relative to the needle.
The corresponding recess or recesses; or corresponding projection or projections of the third retaining means, are desirably provided on the third part.
The visual indication means may comprise alignable markings on any of the first, second and third parts.
The second part preferably comprises a portion proximal of the restrictive part which accepts the needle in any orientation, and desirably receives the distal end of the needle when the assembly is in a rest condition.
The or each variable length portion of the housing preferably comprises a flexible cover around the needle, and the cover is preferably substantially inelastic. The or each variable length portion preferably comprises a spring urging said portion to its maximum length. The springs preferably extend substantially co-axially around the needle. The or each spring preferably extends respectively between the first and second parts; the first and third parts; or second and third parts. The cover may be mounted on, or integral with, the spring.
The assembly may be arranged to only permit the needle to extend from the housing if the second part is moved to a required orientation substantially before the second part is moved significantly towards the first part. At least an inner part of the restrictive part of the housing may be provided with indents in the inner cross-section thereof such that the end of the needle will tend to catch in a one of the indents if not fully in the required orientation when the second part is moved towards the first part, to prevent further rotation towards the required orientation.
The assembly is preferably arranged to be mountable on a needle instrument. The assembly is preferably releasably mountable on a needle instrument, and mounting means may be provided on the first part.
The invention further provides a needle instrument incorporating a needle assembly according to any of the preceding thirty one paragraphs.
The invention also provides a syringe incorporating a needle assembly according to any of said preceding thirty one paragraphs.